MICROBIOTA FROM DECCAN INTERTRAPPEAN DEPOSITS OF THE WESTERN (KUTCH) AND CENTRAL (MADHYA PRADESH) PENINSULAR INDIA

Abstract

Sedimentary deposits intercalated within the Deccan volcanics of peninsular are of great importance in understanding the evolution of India’s faunal and floral biodiversity as well as in gaining insights into India’s paleoenvironments, paleogeographic setting as well as intercontinental biogeographic relations around the Cretaceous-Paleocene (K-Pg) boundary, the time when the Indian plate was drifting northwards prior to its collision with Asia in the early Paleogene. These intertrappean deposits represent a non-eruptive phase or the period when there was no volcanic activity in a given region. During the past four decades, a number of intertrappean localities have been studied along the eastern and southeastern fringe of the Deccan volcanic province, resulting in enormous amount of data on the intertrappean biotas with significant implications. However, in contrast to the intertrappean deposits fringing the eastern and southeastern margins of the Deccan volcanic province, fossil biotas from the west-central portion of the volcanic province lying in the lower reaches of the Narmada valley of Madhya Pradesh (District Dhar), which forms the Malwa sub-province of the Deccan volcanic province, has received relatively little attention. This study presents the first systematic account of the Deccan intertrappean faunas recovered from three sections (Kesavi, Mohanpura, Bhagwania) in District Dhar of the lower Narmada valley, Madhya Pradesh. In addition, two sections in District Kutch (Gujarat) and Chhindwara (Madhya Pradesh) have also been investigated. The main objective of this doctoral investigation is to document the paleoenvironmental, paleogeographic, paleobiogeographic and biogeographic implications of the recovered fossil biota from the lower Narmada valley. The Kesavi intertrappean biota includes freshwater fishes (Lepisosteus, osteoglossids, serranids, Enchodus), discoglossid anurans, cordyliform lizards, found in association with pulmonate gastropods and charophytes. A major find reported from the Kesavi intertrappeans is a cordyliform lizard (a new, recently named taxon Deccansaurus palaeoindicus) which has been discovered for the first time from the Indian subcontinent. Its similarity with the contemporary cordyliform Konkasaurus from the late Cretaceous of Madagascar, suggests close biogeographic links between India and Madagascar during the latest Cretaceous, (Maastrichtian) in spite of the fact that these two landmasses remained physically separated since ~88 Ma. Cordyliforms are a living clade confined to Africa.